I'm a Ubuntu 12.04 LTS user, and I want something that disconnect the Internet at a specific time. Here in this answer, there was an option in modem manager to disconnect the internet at specific time but unfortunately this has not worked for me.
Why I'm asking for such software
Sometimes I use night pack, my night pack time limit is 0000 hr - 0600 hr. So I start to download something e.g. a movie and then I go to sleep. One time it happened that I woke up at 0800 hr, the download was already over at 0430, but after 0600 some MB's were used, and cost of those extra MB's was more than my night pack! And so I need some helpful software.